Living specimen induction chamber

ABSTRACT

The invention described herein provides an induction chamber used to sedate one or more living specimens. The induction chamber comprises at least one gas inlet through which anesthesia gas and oxygen are supplied. To minimize escape of anesthetizing gas is into the ambient room or surroundings, the induction chamber includes a gas outlet or port that draws anesthesia gas. The induction chamber also comprises a device that obstructs gas flow through the gas outlet based on the position of the door. In one chamber design, when the door closes, the gas outlet is blocked. Thus, opening the door to the induction chamber causes anesthesia gas is to be drawn through the outlet while closing the door allows anesthesia gas to collect in the chamber and sedate any specimens located therein.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of and claims priority under 35 U.S.C.§120 from co-pending U.S. patent application Ser. No. 10/370,031, filedFeb. 19, 2003 and entitled, “LIVING SPECIMEN INDUCTION CHAMBER”; the10/370,031 application claims priority under 35 U.S.C. 119(e) from U.S.Provisional Patent Application No. 60/385,397; the 10/370,031application is also a continuation-in-part of U.S. patent applicationSer. No. 10/081,040 entitled “MULTIPLE OUTPUT ANESTHESIA SYSTEM” byDalgetty et al., filed on Feb. 20, 2002; each of these PatentApplications is incorporated by reference herein for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to anesthesia delivery systemsand imaging systems. In particular, the present invention relates toinduction chambers used to anesthetize mammalian specimens in imagingand research applications.

BACKGROUND OF THE INVENTION

One new and specialized type of imaging involves the capture of lowintensity light—often on the order of only tens to hundreds ofphotons—from a light-emitting sample. The low intensity light source maybe emitted from any of a variety of light-emitting sources within aliving specimen, e.g., luciferase expressing cells within a mouse. Thesource of the light indicates portions of the sample, such as tracedmolecules in a particular portion of a mammalian specimen, where anactivity of interest may be taking place. Some specialized in-vivoimaging applications include analysis of one or more representations ofemissions from internal portions of a specimen superimposed on aphotographic representation of the specimen. The photographicrepresentation provides the user with a pictorial reference of thespecimen. The luminescence representation indicates portions of thespecimen where an activity of interest may be taking place.

Obtaining a luminescence representation often involves image captureover an extended period of time, e.g., minutes, in a specialized imagingbox. The imaging box is a custom-made apparatus designed to tightlycontrol the amount of light in the box and minimize light entering fromthe surrounding room. The living specimen is typically anesthetizedduring imaging to prevent movement that may affect prolonged imagecapture.

An induction chamber is typically used to anesthetize the livingspecimen before being placed in the imaging box. A laboratory technicianor researcher places one or more conscious living specimens in theinduction chamber. A combination of anesthetizing gas and oxygen is thensupplied to the induction chamber. The specimen remains in the inductionchamber until it loses consciousness, or is similarly sedated, and isthen transported by the laboratory technician into the imaging box.Transporting living specimens in and out of the induction chamber mayallow the anesthesia gas to escape into the ambient surroundings.Preferably, the amount of anesthesia gas that escapes is minimized.

Conventional induction chambers rely on a purge system to manageanesthesia gas escape. The purge system forces high-pressure oxygen intothe induction chamber before the door or user access is opened. Apassive exhaust port leading from the induction chamber interiorreceives the high-pressure purge oxygen and any gases present in theinduction chamber before the purge. One problem with purge systems isthat the high burst of oxygen, and/or removal of all anesthetizing gas,frequently awakens any living specimens in the induction chamber. When asingle living specimen is in the induction chamber, this is clearlydefeating to the intended induction chamber purpose. Lab technicianshowever often work with multiple living specimens at a single time andpurging the induction chamber to remove one specimen may then lead tomore than one specimen awakening.

In view of the foregoing, an improved induction chamber capable ofanesthetizing one or more living specimens would be desirable.

SUMMARY OF THE INVENTION

The present invention relates to an induction chamber used to sedate oneor more living specimens. The induction chamber comprises at least onegas inlet through which anesthesia gas and oxygen are supplied. Tominimize escape of anesthetizing gas is into the ambient room orsurroundings, the induction chamber includes a gas outlet or port thatdraws anesthesia gas. A negative or vacuum pressure is applied to thegas outlet. The negative pressure draws gases from within the inductionchamber, and may draw gases from the ambient surroundings around theinduction chamber when a door allowing a lab technician access to theinduction chamber interior opens. The induction chamber also comprises adevice that obstructs gas flow through the gas outlet based on theposition of the door. In one embodiment, when the door closes, the gasoutlet is blocked. Thus, opening the door to the induction chambercauses anesthesia gas is to be drawn through the outlet while closingthe door allows anesthesia gas to collect in the chamber and sedate anyspecimens located therein. The induction chamber is particularly usefulfor sedating a living specimen prior to insertion in an imaging box orchamber.

In one embodiment, the gas outlet is near the door. In a specificembodiment where the door is on the top portion of the chamber, the gasoutlet is vertically disposed on the top half of the induction chamber.In this case, suction of anesthesia gas removes a top layer ofanesthesia gas from a top portion of the induction chamber interiorcavity. One or more living specimens resting on the bottom half of theinduction chamber interior cavity are thus still exposed to anesthesiagas while the door is open. This allows the lab technician to remove oneor more specimens without awakening the other living specimens.

In one aspect, the present invention relates to an induction chamber fordelivering anesthesia gas to a living specimen. The induction chambercomprises a set of walls defining an interior cavity. The inductionchamber also comprises a door that is movable between an openedcondition that enables gaseous communication between the interior cavityand the environment exterior to the induction chamber through anopening, and a closed condition that seals the interior cavity from theenvironment exterior to the induction chamber. The induction chamberfurther comprises a gas inlet disposed in one of the set of walls andcapable of providing anesthesia gas to the interior cavity. Theinduction chamber additionally comprises a gas outlet disposed in one ofthe set of walls and capable of drawing anesthesia gas from the interiorcavity when the door is in the opened condition. The induction chamberalso comprises a gas outlet obstruction that varies flow of anesthesiagas from the interior cavity through the gas outlet based on theposition of the door.

In another aspect, the present invention relates to a method of using aninduction chamber. The induction chamber comprises a set of walls thatdefine an interior cavity. The induction chamber also comprises a doorthat is movable between an opened condition and a closed condition. Themethod comprises supplying an anesthesia gas into the interior cavity.The method also comprises drawing anesthesia gas through a gas outletdisposed on one of the set of walls when the door is in the openedcondition. The method further comprises obstructing gas flow through thegas outlet when the door is in the closed condition.

In yet another aspect, the present invention relates to an imagingsystem for capturing an image of a living specimen with a camera. Thesystem comprises an imaging box having a set of walls enclosing aninterior cavity and a camera mount configured to position the camera toview the living specimen in the interior cavity while the livingspecimen is anesthetized. The system comprises an induction chamber. Theinduction chamber comprises a set of walls defining an interior cavity.The induction chamber also comprises a door that is movable between anopened condition that enables gaseous communication between the interiorcavity and the environment exterior to the induction chamber through anopening, and a closed condition that seals the interior cavity from theenvironment exterior to the induction chamber. The induction chamberfurther comprises a gas inlet disposed in one of the set of walls andcapable of providing anesthesia gas to the interior cavity. Theinduction chamber additionally comprises a gas outlet disposed in one ofthe set of walls and capable of drawing anesthesia gas from the interiorcavity when the door is in the opened condition. The induction chamberalso comprises a gas outlet obstruction that varies flow of anesthesiagas from the interior cavity through the gas outlet based on theposition of the door.

These and other features of the present invention will be described inmore detail below in the detailed description of the invention and inconjunction with the following figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1 is a perspective view of an imaging system in accordance with oneembodiment of the present invention.

FIG. 2A illustrates a top prospective view of the front of the inductionchamber of FIG. 1 in accordance with one embodiment of the presentinvention.

FIG. 2B illustrates a top prospective view of the back of inductionchamber of FIG. 1.

FIG. 2C illustrates a top prospective view of the door underside for theinduction chamber of FIG. 1.

FIG. 2D illustrates a side cross sectional view of induction chamber ofFIG. 1 taken through the lateral midpoint.

FIG. 3 illustrates a process flow for using the induction chamber ofFIG. 1 in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description of the present invention, numerousspecific embodiments are set forth in order to provide a thoroughunderstanding of the invention. However, as will be apparent to thoseskilled in the art, the present invention may be practiced without thesespecific details or by using alternate elements or processes. In otherinstances well known processes, components, and designs have not beendescribed in detail so as not to unnecessarily obscure aspects of thepresent invention.

Imaging System

In one aspect, the present invention relates to imaging systems forcapturing an image of a low intensity light source. FIG. 1 illustratesan imaging system 10 configured to capture photographic and luminescenceimages in accordance with one embodiment of the present invention.Imaging system 10 may be used for imaging a low intensity light source,such as luminescence from luciferase-expressing cells, fluorescence fromfluorescing molecules, and the like. The low intensity light source maybe emitted from any of a variety of light-emitting samples which mayinclude, for example, animals containing light-emitting molecules, e.g.,various mammalian subjects such as mice containing luciferase expressingcells.

Imaging system 10 comprises an imaging box 12 having a door and wallsthat define an interior cavity that is adapted to receive alight-emitting sample in which low intensity light, e.g.,luciferase-based luminescence, is to be detected. Imaging box 12 isoften referred to as “light-tight”, e.g., it seals out essentially allof the external light from the ambient room from entering the box 12,and may include one or more seals that prevent light passage into thebox when the door is closed. The seals may also be effective to preventanesthesia gases used within box 12 from escaping into the ambient room.Imaging box 12 is suitable for imaging including the capture of lowintensity light on the order of individual photons, for example.

Imaging box 12 includes an upper housing 16 adapted to receive a camera.A high sensitivity camera 20, e.g., an intensified or a charge-coupleddevice (CCD) camera, is mounted on top of upper housing 16 andpositioned above imaging box 12. CCD camera 20 is capable of capturingluminescent and photographic (i.e., reflection based images) images of asample placed within imaging box 12. CCD camera 20 is cooled by asuitable source such as a refrigeration device 22 that cycles acryogenic fluid through the CCD camera via conduits 24. A suitablerefrigeration device is the “CRYOTIGER” compressor, which can beobtained from IGC-APD Cryogenics Inc., Allentown, Pa. Other methods,such as liquid nitrogen, may be used to cool CCD camera 20.

Imaging system 10 also includes an anesthesia delivery system thatdelivers anesthesia gas and oxygen. The anesthesia delivery systemincludes console 52, induction chamber 54 (FIGS. 2A-2D), and a gasdelivery device 56. Console 52 allows a user or lab technician tocontrol flow of anesthesia gas and oxygen from one or more gas outletson the console. The output of console 52 is a combination oflow-pressure oxygen and anesthesia gas. As shown, console 52 includestwo gas delivery outlets: a first gas delivery outlet for servicing gasdelivery device 56 and a second delivery outlet 71 that servicesinduction chamber 54.

Oxygen delivery conduit 58, such as a rubber tube or hose, is operablycoupled to an oxygen inlet of main console 52 and an outlet of an oxygensupply source. For example, the oxygen supply source may be a highpressure oxygen cylinder or conventional medium pressure wall outlet.Conduit 60 is coupled to an outlet of main console 52 and coupled toinlet of induction chamber 54 and allows gaseous communication betweeninduction chamber 54 and console 52.

Induction chamber 54 receives oxygen and anesthesia gas from conduit 60.Induction chamber 54 allows a user to anesthetize one or more livingspecimens that fit within induction chamber 54, and will be described infurther detail with respect to FIGS. 2A-D. A passive gas outlet isincluded in a side wall of induction chamber 54 and coupled to conduit77. The passive gas outlet and conduit 77 allow gases to flow passivelyfrom induction chamber 54. The gases in conduit 77 are provided tofilter 78. In one embodiment, the anesthesia gas is isoflurane andfilter 78 is a charcoal filter that removes unused isoflurane thatpasses therethrough. A filter model number 80120 F/Air Cannister asprovided by A. M. Bickford of Wales Center, N.Y. is suitable for use asfilter 78. Filter 78 outputs primarily oxygen. As shown, filter 78outputs oxygen into the ambient room.

An active gas outlet is also included in a top portion of a side wall ofinduction chamber 54 and is coupled to conduit 79. The active gas outletand conduit 79 actively draws gases from induction chamber 54 andprovides them to filter 81. A pump 83 provides a negative pressure tothe active gas outlet and conduit 79 the draws oxygen and anesthesia gasfrom the interior of induction chamber 54. The active gas outlet will bedescribed in further detail below. In one embodiment, pump 83 is modelnumber VP0125 as provided by Medo USA, of Cherry Hill, Ill.

Conduit 62 allows gaseous communication between console 52 and gasdelivery device 56. Gas delivery device 56 may be placed within box 12and includes multiple specimen interfaces for communicating anesthesiagas to one or more living specimens. For example, box 12 typicallyincludes a stage that supports one or more mice to be imaged, and gasdelivery device 56 may be place on the stage in proximity to the mice. Alight-sealed hole 27 is included in a side wall of box 12 to allow a gasconduit 62 to pass therethrough while device 56 is in box 12. Conduit 62may comprise tubing or a suitable hose. For example, ⅜ inch OD ¼ inch ID90 durometer viton rubber tubing is suitable for use as conduits in FIG.1.

An image-processing unit 26 optionally interfaces between camera 20 anda computer 28 through cables 30 and 32 respectively. Computer 28, whichmay be of any suitable type, comprises a main unit 36 that typicallycontains hardware including a processor, memory components such asrandom-access memory (RAM) and read-only memory (ROM), and disk drivecomponents (e.g., hard drive, CD, floppy drive, etc.). Computer 28 alsoincludes a display 38 and input devices such as a keyboard 40 and inputmouse 42. Computer 28 is in communication with various components inimaging box 12 via cable 34. To provide communication and control forthese components, computer 28 includes suitable processing hardware andsoftware configured to provide output for controlling any of the devicesin imaging box 12. The processing hardware and software may include anI/O card, control logic for controlling any of the components of imagingsystem 10, and a suitable graphical user interface that facilitates userinteraction with imaging system 10. Components controlled by computer 28may include camera 20, motors responsible for camera 20 focus, motorsresponsible for position control of a platform supporting the livingspecimens, the camera lens, f-stop, etc.

Computer 28 may also include suitable processing hardware and softwarefor camera 20 such as additional imaging hardware and software,calibration software, and image processing logic for processinginformation obtained by camera 20. The logic in computer 28 may take theform of software, hardware or a combination thereof. Computer 28 alsocommunicates with a display 38 for presenting imaging information to theuser. For example, the display 38 may be a monitor, which presents animage measurement graphical user interface (GUI) that allows a user toview imaging results and also acts an interface to control the imagingsystem 10.

Induction Chamber

FIGS. 2A-2D illustrate induction chamber 54 of FIG. 1 in accordance withone embodiment of the present invention. Induction chamber 54 allows auser to anesthetize one or more living specimens that fit withininduction chamber 54 and is also commonly referred to as a ‘knockdownbox’. Induction chamber 54 includes an interior cavity sized to receiveliving specimens and a gas inlet that allows a user to supply ananesthesia gas to the interior cavity, as described in greater detailbelow. While induction chamber 54 will now be described as an apparatus,those skilled in the area will recognize that the present inventionencompasses a method of using the apparatus based on the functionalcomponents of the induction chamber.

FIG. 2A illustrates a top prospective view of the front of inductionchamber 54. FIG. 2B illustrates a top prospective view of the back ofinduction chamber 54. FIG. 2C illustrates a top prospective view of theunderside of door 124. FIG. 2D illustrates a side cross sectional viewof induction chamber 54 taken through the lateral midpoint of side walls112 a and 122 d.

Referring initially to FIG. 2A, induction chamber 54 includes fourvertical side walls 122 a-d fixed to a bottom 123. Side walls 122 a-dinclude front wall 122 a, side wall 122 b, side wall 122 c, and backwall 122 d. Side walls 122, bottom 123 and top wall 127 then comprise aset of walls that define an interior cavity 128 (FIG. 2D) withininduction chamber 54. As shown in FIG. 2D, interior cavity 128 issufficiently sized to receive multiple living specimens 134. A cavityvolume of about 2 to about 8 liters is suitable for many inductionchambers. In one embodiment, interior cavity 128 has a cavity volume ofabout 3 to about 4 liters. Interior cavity 128 may include a stage 143or platform that the living specimens rest upon.

Side walls 122, bottom 123 and top wall 127 each comprise a transparentmaterial that allows a user to view interior chamber 128. In a specificembodiment, lexan, a transparent plastic such as polycarbonate, or atransparent acrylic, are used for the walls of induction chamber 54.Using transparent walls for induction chamber 54 advantageously allows auser to view the interior of induction chamber 54. Walls for inductionchamber 54 may very in thickness from about ⅛ inch thick to about 1 inchthick, for example.

Induction chamber 54 comprises a door or user access port that allowsuser access to interior cavity 128. As shown in FIG. 2A, inductionchamber 54 comprises a door 127 that comprises the top wall of chamber54 and spans the entire top surface area of induction chamber 54 asdefined by side walls 122 a-d. Door 127 is hingeably coupled to backwall 122 d using a pin 144 (FIG. 2B) that passes through a channel 141included in the hinges 125 (FIG. 2A) and a channel 142 included in door127 (FIG. 2C). Hinges 125 are screwed to the outside of back wall 122 d(FIG. 2B).

Door 127 is movable between a closed condition and various openedconditions. FIG. 2A illustrates the closed condition for door 127 andinduction chamber 54. In the closed condition as shown, door 127 restsupon the top portion of walls 122 and seals interior cavity 128 from theenvironment exterior to induction chamber 54. In one opened condition,door 127 enables user access into interior chamber to insert or removeliving specimens. In the opened conditions, door 127 enables gaseouscommunication, or gaseous flow, between interior cavity 128 and theenvironment exterior to induction chamber 54 through an opening. Thesize and profile of the opening will depend on the angle door 127 makesrelative to its closed position as shown. Thus, when door 127 isinitially opened from the position shown in FIG. 2A, a crack between thetop portion of each side wall 122 in door 127 creates an opening thatallows anesthesia gas and oxygen to flow between interior chamber 128and the environment external to induction chamber 54.

Seal 145 is disposed in a recess that runs perimetrically about a topportion of each side wall 122 (FIG. 2B). As shown in FIG. 2A, seal 145runs 360 degrees about the top opening of interior cavity 128. Seal 145is a compressible material that prevents gaseous communication betweeninterior cavity 128 and the environment exterior to induction chamber 54when door 127 is in the closed condition. More specifically, when door127 is in the closed position, the bottom surface of door 127 cooperateswith seal 145 to prevent gaseous communication between interior cavity128 and the environment external to induction chamber 54. In a specificembodiment, seal 145 comprises a rubber or silicone.

Clamp 147 is attached side wall 122 a using screws 151. Clamp 147 allowsa user to secure door 127 in the closed position. In addition, clamp 147is vertically disposed such that securing clamp 147 provides acompressive force between the bottom surface of door 127 and seal 145.

Induction chamber receives low-pressure oxygen and anesthesia gas fromconsole 52 and conduit 60. Induction chamber 54 thus includes at leastone gas inlet capable of providing anesthesia gas to the interior cavity128. As shown, induction chamber 54 includes a single gas inlet 130 thatsupplies both anesthesia gas and oxygen from the exterior of inductionchamber 54 to the interior cavity 128. Gas inlet 130 is disposed in alower portion of back wall 122 d and includes a circular port or holethrough back wall 122 d that allows gaseous communication between theinside and outside of induction chamber 54. As shown, gas inlet 130includes an exterior interface 123 (FIG. 2B) that receives conduit 60(FIG. 1). Referring back to FIG. 1, console 52 provides a mixture ofoxygen and anesthesia gas to induction chamber 54. This mixture ispassed into induction chamber 54 through gas inlet 130. Console 52includes controls that allow a user to turn on/off or vary the flowrateof oxygen and anesthesia gas provided to induction chamber 54. It isunderstood that induction chamber 54 may include multiple gas inlets.For example, one inlet may be dedicated to anesthesia gas was a secondgas inlet is dedicated to oxygen supply.

The present invention employs an anesthesia gas to sedate livingspecimens. As the term is used herein, an anesthesia gas refers to anygas or agent that is used to induce any level of anesthetic state,unconsciousness, lack of awareness, or local or general insensibility topain for a specimen interacting with induction chamber 54. The amount ofanesthesia gas is typically determined by the control console 52 ofFIG. 1. A vaporizer included in console 52 may be used to produce theanesthesia gas and add it to low-pressure oxygen. The output of thevaporizer typically comprises a controlled and variable gas mixture oflife sustaining gases and anesthetizing gases. In a specific embodiment,isoflurane is added to low pressure oxygen by passing oxygen across avaporizer that evaporates isoflurane. In this case, the low-pressureoxygen acts as a carrier for the isoflurane, which is added to theoxygen according to the physical characteristics of isoflurane liquidand its temperature. Although the present invention is primarilydescribed with respect to using only a single anesthesia gas,isoflurane, it is understood that an anesthesia gas of the presentinvention may include multiple anesthesia gases, as one of skill in theart will appreciate.

Induction chamber 54 also comprises a gas outlet 150 capable of drawinganesthesia gas from interior cavity 128 when door 127 is in an openedcondition. Gas outlet 150 is disposed in an upper portion of back wall122 d and includes a circular port or hole through back wall 122 d thatallows gaseous communication between the inside and outside of inductionchamber 54. As shown, gas outlet 150 includes an exterior interface 152(FIG. 2B) that receives conduit 79, which exhausts gases from inductionchamber 54 to filter 81 (FIG. 1).

Gas outlet 150 actively draws and collects anesthesia gas from interiorcavity 128, and actively draws and collects anesthesia gas from theenvironment external to induction chamber 54 when door 127 is in anopened condition. To do so, gas outlet 150 is in gaseous communicationwith a negative pressure supply such as vacuum pump 83 (FIG. 1). Vacuumpump 83 provides a negative pressure to gas outlet 150 that draws gasesinto outlet 150. In one embodiment, the negative pressure is negativerelative to the pressure within interior chamber 128. In anotherembodiment, the native pressure is negative relative to the environmentexterior to induction chamber 54. This creates a draft through anyopening created by door 127 that causes air and anesthesia gas to bedrawn from the external environment, to pass in through interior cavity128, and into gas outlet 150. Thus, with suitable pressure from pump 83,anesthesia gases about to escape interior cavity 128 when door 127 opensmay be drawn and collected by gas outlet 150 before they escape. Inaddition, anesthesia gases that have escaped interior cavity 128 may bedrawn and collected by gas outlet 150 when door 127 is opened.

The flowrate of anesthesia gas and other gases through gas outlet 150may vary. In one embodiment, gas outlet 150 draws gases from interiorcavity 128 at a flowrate through gas outlet 150 greater than the volumeof interior cavity 128 per minute. In a specific embodiment, gas outlet150 draws gases from interior cavity 128 at a flowrate from about 0L/min to about 8 L/min.

Induction chamber 54 also comprises a gas outlet obstruction 160 thatvaries flow of anesthesia gas from interior cavity 128 through gasoutlet 150 based on the position of door 127. Typically, gas outletobstruction 160 varies flow of anesthesia gas from interior cavity 128by obstructing gas outlet 150 in some manner. Thus, gas outletobstruction 160 may plug, cap, cork, block, prevents, or otherwiseimpair gas flow through gas outlet 150.

As shown in FIG. 2D, gas outlet obstruction 160 comprises a bracket 162having a portion 162 a that rests flat against the bottom side of door127 and is attached to door 127 using screws 164. Bracket 162 also has aportion 162 b that is positioned proximate to gas outlet 150 when door127 is in the closed position. Attached to portion 162 b is screw 166,washer 168, compressible material 170 and spacer 172. Screw 166 fastenswasher 168, compressible material 170 and spacer 172 to portion 162 b.Compressible material 170 interfaces with gas outlet 150 to seal theoutlet 150 when door 127 is in the closed position. Thus, portion 162 bis proximate to gas outlet 150 such that compressible material 170 sealsthe outlet 150 when door 127 is in the closed position. Together,portion 162 b and perimeter material of gas outlet 150 combine tocompress the compressible material 170 when door 127 is in the closedcondition. FIG. 2D illustrates gas outlet obstruction 160 when door 127is in the closed position. Here, gas outlet obstruction 160 restrictsflow of anesthesia gas from interior cavity 128 through gas outlet 150.Washer 168 allows screw 166 to tighten without compressing a localizedportion of compressible material 170. Spacer 172 allows a user to changethe thickness of compressible material 170 or vary the force appliedbetween portion 162 b and the perimeter material of gas outlet 150 oncompressible material 170.

In a simplified embodiment, gas outlet obstruction 160 simply comprisesa compressible material that spans the entire back side of portion 162 bof bracket 162. Similar to the previous case, the this simplifiedembodiment seals gas outlet 150 when door 127 is in the closedcondition. In addition, the gas outlet obstruction 160 allows gas toflow from interior cavity 128 through gas outlet 150 when door 127 is inan opened condition.

In one embodiment, gas outlet 150 is disposed in the top half of a sidewall 122. In this case, anesthesia gas is introduced near the bottom ofinduction chamber 54 and collects in interior cavity 128 when door 127is closed. When door 127 opens, gas outlet 150 draws anesthesia gas fromthe top portion of interior cavity 128. As long as the flowrate throughgas outlet 150 is not excessive, this may result in a temporary twolayer gaseous formation within interior cavity 128. The top layercomprises gases that move toward gas outlet 150. The bottom layercomprises anesthesia gas and oxygen supplied by gas inlet 123. Anadvantage of this design is that even with door 127 opened for shortperiods of time, living specimens is disposed near the bottom ofinduction chamber 54 may not be entirely devoid of anesthesia gas.

In one embodiment, passive gas outlet 132 is disposed in back wall 122c. Passive gas outlet 132 passively exhausts anesthesia gas frominterior cavity 128 based on positive pressure in interior cavity 128relative to conduit 77. Typically, this occurs when door 127 is in theclosed condition and gas outlet 150 is obstructed. In this case,continual anesthesia gas and oxygen supply into interior cavity 128builds pressure within the interior cavity and causes passive gas flowthrough gas outlet 132. Gas outlet 132 is disposed in a lower portion ofback wall 122 d and includes a circular port or hole through back wall122 d that allows gaseous communication between the inside and outsideof induction chamber 54. As shown, passive gas outlet 132 includes anexterior interface 129 (FIG. 2B) that receives conduit 77, whichexhausts gases from induction chamber 54 to filter 78 (FIG. 1).

FIG. 3 illustrates a process flow 200 for using induction chamber 54 ofFIG. 1 in accordance with one embodiment of the present invention.Processes in accordance with the present invention may include up toseveral additional steps not described or illustrated herein in ordernot to obscure the present invention.

In operation, a user opens door 127 (FIG. 1) and places a livingspecimen within the interior of induction chamber 54. Closing door 127seals the interior of induction chamber 54 from the ambient room via theinterface of seal 145 and door 127. In addition, a gas outletobstruction obstructs gas flow through gas outlet 150 when door 127 isin the closed condition (206). In one embodiment, the gas outletobstruction is attached to the door 127 and fully seals gas outlet 150when door 127 is in the closed condition and fully prevents gas fromflowing through gas outlet 150+.

After induction chamber 54 is sealed, oxygen and anesthesia gas aresupplied to the interior via console 52 and gas inlet 130 (202). Aspressure in the interior cavity builds, exhaust gases may be passivelyremoved from induction chamber 54 via a passive exhaust included ininduction chamber 54. Gas flows into the passive exhaust based on apositive pressure accumulating inside the chamber relative to thepassive exhaust. After anesthesia delivery to the living specimen iscomplete, e.g. when the specimen has been anesthetized, door 127 may beopened to allow a lab technician to remove one or more specimens.

Opening door 127 ceases obstruction of gas outlet 150. This causesanesthesia gas to be drawn through gas outlet 150 from the interiorchamber when door 127 is in the opened condition (204). In oneembodiment, the gas outlet draws gases from the interior chamber at aflow rate greater than the volume of the interior chamber per minute.This is done with a negative pressure that is applied to the gas outlet,e.g., via a pump.

When used in the imaging system 10 of FIG. 1, process flow 200 may alsoinclude various additional actions related to imaging the specimen afterit has been sedated. For example, a user may remove a living specimenfrom the interior cavity when the door is in the opened condition, placethe living specimen in the imaging box, and image the living specimen,or a portion thereof, using the imaging system.

In early tests, induction chamber 54 produced improved results for itsintended purpose when gas outlet 150 and obstruction 160 were used. Inmany cases, induction chamber 54 reduced the amount of anesthesia gasintroduced into the ambient surroundings by a factor of about 4-5relative to an induction chamber without an active gas outlet and gasoutlet obstruction. In addition, opening door 127 did not result infrequent living specimen arousal—for both specimens being removed andresting temporarily while another specimen was being removed.

While this invention has been described in terms of several preferredembodiments, there are alterations, permutations, and equivalents whichfall within the scope of this invention which have been omitted forbrevity's sake. For example, although induction chamber 54 has beendescribed with respect to an active gas outlet in a side wall, it isunderstood that other designs include the gas outlet in other positionssuch as a top wall. It is therefore intended that the scope of theinvention should be determined with reference to the appended claims.

1. A method of using an induction chamber associated with an imagingsystem including an imaging box, the induction chamber comprising a setof walls that define an interior cavity and comprising a door that ismovable between an opened condition and a closed condition, the methodcomprising: supplying an anesthesia gas into the interior cavity of theinduction chamber; drawing anesthesia gas through a gas outlet disposedon one of the set of walls when the door is in the opened condition;obstructing gas flow through the gas outlet when the door is in theclosed condition; removing a living specimen from the interior cavitywhen the door is in the opened condition; placing the living specimen inthe imaging box; and imaging the living specimen using the imagingsystem.
 2. The method of claim 1 wherein the gas outlet is sealed by agas outlet obstruction attached to the door when the door is in theclosed condition.
 3. The method of claim 1 further comprising passivelyexhausting anesthesia gas from the interior cavity based on increasedpressure in the interior cavity relative to the gas outlet when the dooris in the closed condition.
 4. The method of claim 1 wherein the gasoutlet draws gases from the interior chamber at a flow rate greater thanthe volume of the interior chamber per minute.
 5. The method of claim 4wherein the gas outlet withdraws gases from at a flow rate about 0 L/minto about 8 L/min.
 6. The method of claim 1 wherein the gas outlet isdisposed in the top half of a vertical wall of the set of walls.
 7. Themethod of claim 1 further comprising applying negative pressure to thegas outlet.
 8. The method of claim 7 wherein a pump provides thenegative pressure to the gas outlet.
 9. The method of claim 7 whereinthe negative pressure is negative relative to the environment exteriorto the induction chamber.
 10. An imaging system for capturing an imageof a living specimen with a camera, the system comprising: an imagingbox having a set of walls enclosing an imaging cavity and a camera mountconfigured to view the living specimen in the imaging cavity; and aninduction chamber comprising: a set of walls defining an interiorcavity, a door that is movable between an opened condition that enablesgaseous communication between the interior cavity and the environmentexterior to the induction chamber through an opening, and a closedcondition that seals the interior cavity from the environment exteriorto the induction chamber through the opening, a gas inlet disposed inone of the set of walls and capable of providing anesthesia gas to theinterior cavity, a passive gas outlet disposed in one of the set ofwalls and configured to passively exhaust anesthesia gas from theinterior cavity based on positive pressure in the interior cavity whenthe door is in the closed condition; and a gas outlet obstruction thatvaries flow of anesthesia gas from the interior cavity through the gasoutlet based on the position of the door.
 11. The induction chamber ofclaim 10 further comprising a second gas outlet disposed in one of theset of walls.
 12. The induction chamber of claim 10 wherein the gasoutlet obstruction is configured to permit gas to flow from the interiorcavity through the gas outlet when the door is in the open condition.13. The induction chamber of claim 10 wherein the gas outlet obstructionis configured to prevent flow of anesthesia gas from the interior cavitythrough the gas outlet when the door is in the closed condition.
 14. Theinduction chamber of claim 13 wherein the gas outlet obstruction isattached to the door and seals the gas outlet when the door is in theclosed condition.
 15. The induction chamber of claim 14 wherein the gasoutlet obstruction comprises a compressible material that is compressedby interface with the gas outlet when the door is in the closedcondition.
 16. The induction chamber of claim 10 wherein the doorcomprises a top wall for the set of walls.
 17. The induction chamber ofclaim 10 wherein the gas outlet is disposed in the top half of avertical wall of the set of walls.
 18. The induction chamber of claim 10wherein the gas outlet is in gaseous communication with a pump thatprovides negative pressure to the gas outlet.
 19. The induction chamberof claim 18 wherein the negative pressure is negative relative to theenvironment exterior to the induction chamber.
 20. The induction chamberof claim 10 further comprising a compressible seal that facilitatessealing of the interior cavity from the environment exterior to theinduction chamber when the when the door is in the closed condition. 21.The induction chamber of claim 10 wherein the set of walls comprise atransparent material that allows view of the interior chamber.